Method of improving the appearance of silk fabrics



Patented Nov. 17, 1936 PATENT OFFICE LIETHOD F IMPROVING THE APPEARANCE0F SILK FABRICS Warren T. Reddish, Cincinnati, Ohio, assig'nor to EmeryIndustries, Inc., Cincinnati, Ohio, a

corporation of Ohio No Drawing. Application January 31, 1933, Serial.No. 654,554

6 Claims.

This-invention relates to a new art, method, and process of cleaninggarments, fabrics, textiles, cloth, rugs and articles of like naturewhich,

I for the sake of convenience, throughout the remainder of thedescription, will be designated by the term fabrics unless otherwisespecifically identified.

This application is a continuation in part of co-pending applicationSerial No. 590,981, filed February 4, 1932, and now issued into PatentNo.

In view of the fact that the invention lends itself to being practicedin so-called dry cleaning establishments, on the classes of articlesusually cleaned there and with the types of equipment usually usedthere, the present invention is described and claimed as an improvementin the dry cleaning art. However, the physical chemistry utilized inpracticing this invention and the results obtained, are so contrary tothe principles and go so far beyond results now designated by the termdry cleaning", that one might classify the fabric cleaning developmentof this invention as an entirely new art.

In .order to comprehend the true novelty of principle of this invention,a brief review of the theories of previously known methods of cleaningfabrics is requisite. Cleaning fabrics has been accomplished in the pasteither by a soap and water process or by the dry cleaning process.

The dry cleaning process differs in principle from the wet washingprocess.

In the wet washing process the dirt particles on the fabric are removedby emulsification and saponiflcation of the oils and greases which-bindthe particles to the fabric. complished by washing the fabrics with theordinary fatty acid soaps which possess emulsifying powers in watersolution and liberate alkali by hydrolysis which combines with thesaponifiable oils present. These fatty acid soaps also lower the surfacetension of the solution which accelerates the detergent action byincreasing the rate of penetration of the .soap and water into thefabric. The highly water soluble soil which may also be present-isremoved, of course, by the solvent action of the water. This process isinjurious to a majority of typesof fabric because it often causesshrinkage, fading or disfiguration.

- 50 In the dry' cleaning industry to which this .invention is directeda conventional cleaning solvent is employed of the type exemplified by avolatile hydrocarbon or chlorinated hydrocarbon,

naphtha, carbon tetrachloride and trichlor- This is usually ac the morecommonly used of which are gasoline,

ethylene. The term dry cleaning solvent" will be hereinafter used todesignate the class of solvents set forth above. At present, the drycleaning process is usually practiced by treating the fabrics inrotating drum type washers con- 5 taining the cleaning solvent to whichmay be added suitable so-called dry cleaning soaps which decrease staticand lower surface tension. The agitation is continued for from ten tothirty minutes, depending upon the type-of fabrics being 10 treated andtheir condition. During this treatment, the oily or greasy film, whichbinds the dirt particles to the fabrics, is dissolved and the dirtparticles are removed by the agitation of the fabrics in the solvent.The articles are then 15 rinsed in clean solvent and centrifugallyextracted and then dried either in rotary drum type dryers or in heatedrooms. By. this treatment oily and greasy soil is removed withoutshrinkage of the fabric or damage to the sizing and finishing 20materials, the dyes or the fibre itself.

However, marks or disfigurations called water spots which are caused bywater having come in contact with the fabric and roughened. or partiallydissolved the finishing material-and spots 25 caused by solely watersoluble substances, such as perspiration, soft drinks, sugar syrups,andthe like, are not removed by this process. It is,- therefore,necessary to employ water or othersuitable solvents to remove them. Thisis usual- 30 ly done by hand spotting of the affected local areas inorder that the amount of water coming in contact with the fabric may bekept down to a minimum. Due to the labor involved, this operation isrelatively expensive compared to the 35 rest of the process. Moreover,the results obtained depend upon'the skill of the worker and, at best,are highly unsatisfactory.

Such spots may in'some cases be removed by what is called the wet-drytreatment in which 40 the fabric is first immersed in the cleaningsolvent and then, while still saturated with solvent, treated with coldwater or a dilute soap solution for from three to five minutes. Thepresence of the cleaning solvent in the fabric prevents the 5 absorptionof suflicient water to cause appreciable shrinking, loss of sizingmaterial or bleeding of colors, but allows the water to come in contactwith the soluble spots sufficiently to bring about their solution: Thisprocess is tedious, expensive, 5 and may injure a fabric or fail toremove the spots, or both. Obviously, both hand spotting and the wet-drymethods are make-shifts dependent upon artizan skilland judgment. It is,

therefore. to be observed at this point that there I is no existingprocess for cleaning fabrics which is inherently adapted to be used onall types of fabrics to remove all types of soil.

It has always been customary (and still is), to clean fabrics made fromvegetable fibres such as cbtton and linen goods, by washing in soap andwater. This process can also be used on some articles of wool, silk, andrayon, but very great care is required, and generally speaking, thefabrics made from fibre of animal or synthetic origin, which are adaptedto the soap and water washing process, are the exception rather than therule.

Most of the outer garments-worn inthis country at present, such assuits, dresses, coats, etc., are made from fibres of animal origin,usually silk or wool, or both. Such articles are ruined in appearance bysoap and water washing. As a result of the development of cheap cleaningsolvents in the last half of the last century, and as a result of theshifting of population to the large urban centers in which more formalattire prevails, the central dry cleaning plant came into being and itsfacilities became widely available.

The ubiquity of the dry cleaning plants permitted the designers offabrics to develop a great many new sizing and finishing materials,special weaves, peculiar thread twists, and many new and brilliantdyestuffs, which in cleaning would require the special skill andequipment of the large central dry cleaning establishments. On thisaccount, the so-called dry cleaning process has become a tremendousnational industry despite the fact that it does not removawater marksandis inherently adapted to remove from the fabrics but one class of soil,that is, the oil soluble soil, as distinguished from perspiration andother types-of water soluble soil The object of this invention is toprovide an entirely new and novel art, method or prdcess by means ofwhich fabrics are cleansed of substantially all varieties of spotsorsoil without individual attention to each article treated ortheutilizationof artizan skill and judgment.

,This invention resides in a series of recognitions, concepts anddeterminations which have required and received; verification by largescale j commercial operation upon all classesof fabrics normallytendered to dry cleaning establishments throughout the different seasonsof the year during which temperature, humidity, the type ofgarmentsworn, andthe' fabrics employed vary substantially;

"'Thesejrecognitions, concepts and determinationsare asfollowszhnoptimum cleaning action on fabrics is provided-f by a cleaningsolvent containing a--'substantial, predetermined and controlledquantity-of sbsorbed moisture. If the moisture be throughout the cleaninsolvent to a very extreme degree, for instance, that degreewhich'issignifled by a substantial optical clarity of the solution,themthe moisture will not have its usual-deleterious eflects uponthenbre, the dyestufl', or the finish of the fabric being treated. Inother words, even the finest silk evening dress will not be injured bythis treat merit. U

Thus, it is possible to remove the water soluble spots or soil withaquantity of dispersed moisture which is not injurious to the fabricbeing treated, or vice 'versa, a quantity of finely dispersed moisture,so small that it does not injure the fabric being treated, has thecapacity to. remove the watre soluble spots and soil; Still otherwiseexpressed, the invention resides in the con-- cept and determinationthat an appropriate amount of moisture appropriately dispersedthroughout a dry cleaning solvent, possesses the desirable cleaningproperties of water but not the disadvantages.

The next feature of this invention, which is rather unexpected, is thatthe quantity of moisture adapted to produce the best results should becalculated and controlled primarily in relation to the weight of thefabrics treated, rather than in relation to theweight or quantity of thecleaning solvent used. This is due to the fact that the fabrics alwaysabsorb substantially all of the moisture in the cleaning solvent.Therefore, the quantity of moisture contacted with the fabrics ortransferred to the fabrics in the process, is the critical factor ratherthan the ratio of moisture to cleaning solvent in the bath in which thefabrics are treated.

The ratio of moisture to fabric to be used in practicing this inventionmust depend upon the moisture tolerance of the type of fabric beingcleaned. The more specific aspects of the invention may be said toreside in the determination that a useful cleaning action is obtained byagitating the fabrics in a body of cleaning solvent containing aboutfive percent of their weight of moisture and that in many cases, theweight of Y moisture may be increased to thirty percent of the weight ofthe fabrics without injury thereto. For instance, silk garments may becleaned by treatment with between five and fifteen percent of theirweight of moisture, though approximately ten percent is recommended formost large scale commercial runs which include numerous evening gowns.In the case of men's suits, ten to thirty percent of their weight ofmoisture may be used in the cleaning solvent, though fifteen percentseems to produce the best average results on a batch of winter suitscollected from a. high class suburban neighborhood.

It is obvious that if a fine satin evening dress were treated in a bathin which water and naphtha were.simply churned up together, the dresswould become hopelessly water spotted because of large drops of waterabsolutely saturating the dressin many local areas. Such an undesirableeffect diminishes in proportion to the fineness of the particlesofwater. Even a coarse emulsion would ruin asilk dress because theemulsion would saturate completely certain local areas with water-andother local areas with the naphtha. If, however, in the naphtha is sofine that the solution is substantially optically clear, then theabsorption of moisture by thefabric being treated is more the dispersionof the moisture analogous to the absorption of moisture by a fabric in avery seashore. This new process in which a fabric is treated with andtakes on between'flve and thirty percent of its weight of moisture undernormal condamp climate. for instance, on the about in-a container ofcleaning solvent and moisture), results in the removal from the fablookas well or even better than they did when new.

l Inview ofthe fact that moisture does not admix readily with thecleaning solvents in com- .ditions (a large group. of fabricsbeingchurned.

the substantial and requisite quantities of moisture in a statesufficiently fine and dispersed as not to be injurious to the fabrics tobe treated.

Then the desired quantity of moisture may be determined and added foreach batch of fabrics treated. This step is termed "humidifying thecleaning solvent.

It is recommended that the cleaning solvents be constituted waterabsorbent for the maximum amount of moisture requisite for the impendingoperations. If this be done, then it is not necessary to adjust theratio of absorbefacient to cleaning solvent for particular or unusualcon ditions which may arise.

In commercial operations, each batch of fabrics to be cleaned isweighed. Generally speaking, fifty or sixty pounds of fabric areconsidered the maximum load for about fifty gallons of cleaning solvent.Then moisture is added to the cleaning solvent, the amount being basedupon the weight of fabrics being treated. In this connection, attentionshould be paid to the humidity of the atmosphere which normallydetermines the percentage of moisture already in the fabrics. Likewise,it is necessary to take into account the nature of the fabrics beingcleaned and the degree of soil.

It is obvious, of course, that fabrics affected by a large' amount ofexclusively water soluble spots or soil, require treatment :with largerquantities of moisture to effect removal than do fab- ,rics having asmall amount of soil of this type.

When mens rough clothes or the like are being treated, it is possible,if desired, to incorporate so much moisture either before the treatmentor during the treatment, that the cleaning solvent becomes. murkywithout injuring 'the fabrics, though in the case of ladies fine silkdresses and articles of like nature, injury is almost sure to occur ifthe dispersion of moisture be coarse. It must be remembered, in thisregard, that the optical propertiesof the solution are mentioned solelyfor the purpose of' indicating the degree of subdivisionor dispersion ofits moisture content, and that these optical properties have no merit orvirtue in and of themselves.

In many climates and cases it is desirable to dry out the fabrics beforethey are treated, as this step permits the transfer of a larger quantityof moisture to the-"fabric and hencei'providesa.

greater cleaning effect for a given final moisture content of the fabricin question. For instance,.

if silk garments are being treated and the final moisture content issubstantially ove'r fifteen percent, then difllculty is oftenexperienced in the pressing room because of wrinkling. Such garments,however, can be'entirely satisfactorily cleaned and pressed first bydrying them out, then treating them with about ten percent (based 'onthe weight of the fabricsi'of moisture incorporated in the cleaningsolvent.

Throughout the claims the terminology fab-' ric indicated amount ofmoisture is used to de-- rote first of all the novel concept of thisinvention that the amount of moisture employed should be related to theweight of the fabricbeing cleaned, the nature of the fabric beingcleaned, and the condition of the fabric being cleaned, as distinguishedfrom bearing a predetermined percentage relationship to the cleaningsolution as a whole. The selected terminology likewise is employed inthe claims to denote the general moisture fabric relationshiprecommended in the foregoing discussion for operations of the general 7type specified.

The preferred process, as a series of steps, comprises: First, dryingout the fabric to be cleaned, if necessary. Next, the fabrics areweighed. Next, they are given a preliminary dip in a straight solutionof cleaning solvent to get off the worst of the dirt and saturate thefibres with cleaning solvent. Next, moisture is introduced into a secondbatch of cleaning solvent to be used for the crucial treatment, theamount of moisture used being approximately equal to between five andthirty percent of the weight of the fabrics being treated. Ten percentis recommended for fine silks and fifteen percent for mens suits.

After this the fabrics are agitated and churned about in this cleaningbath for a period of between fifteen minutes and half an hour, dependingupon the fabrics and their condition. It is highly desirable to filterthe cleaning solvent during this cleaning process, in order to preventdirt particles being loosely deposited upon the fabrics as they areremoved from the bath. In view of the fact that most of the filters inuse forthis purpose do not permit moisture to pass through them, it isrecommended that this filtering be confined to approximately the lastquarter of the treatment inasmuch as by that time substantially all ofthe moisture present has been absorbed by the fabrics being cleaned.

It is of great importance that the absorbefacient employed in theprocess have the capacity to pass the filters in solution. Otherwise theprocess would not be adapted for use in the modern, well-equipped drycleaning plants, in practically all of which filtration during treatmentis standard practice. The absorbefacient, therefore, must form in thecleaning solvent a stable, permanent solution which will pass thefilters, will not settle out, or change chemically or physically in suchwise as to lose its requisite colloidal properties. I

The fabrics are next given arinse in cleaning solvent after which theyare dried and subjected to relatively routine handling. The filtrationof batch of fabrics to be treated. As pointed out previously, the amountof moisture added must be predetermined and calculated in relation tothe weight and nature of the next batch of fabrics. After the cleaningsolvent accumulates too great an'amount of oil soluble soil orcontamination to be clarified and purified by filtration, it isdistilled and a new moisture absorbent solution constituted. I

As far as is known, it is necessary to use absorbefacients in all of thecleaning solvents at present availableto endowthem with the propertiesrequisite for the practice of this invention. These properties desirablefor the cleaning solvent include: filterability (in the absence ofmoisture) power and capacity to repeatedly absorb substantial quantitiesof moisture in a state of subdivision so fine that the solution issubstantially optically clear; chemical inertness towards all varietiesof fibres, dyestuiis, sizes and finishes; physical and chemicalstability. I

The term absorbefacient is used throughout this disclosure and theclaims to indicate a body which dissolves in a cleaning solvent whichdoes not readily absorb any substantial quantity of moisture and rendersit capable of absorbing a substantial quantity of moisture.

The problem of constituting such a cleaning solvent is believed to be,at present, beyond the ordinary skill of colloidal chemists, and surelybeyond the skill of the dry cleaning industry. Therefore, for thepurpose of assisting the skilled in the art in practicing thisinvention, a number of formulae for absorbefacients is provided. The

claims in the present case are, therefore, limited entirely to the artor method, or process of cleaning fabrics herein disclosed. Theseformulae of absorbefacients are as follows:

, Per cent (1) Sulfonated castor oil containing 31% water 30 Oleic a i21 Potassium oleate 9 Water 3 Naphtha 29.5 Hexa hydro phenol 7.5

The ratio of absorbefacient-to cleaning solvent can be varied, but a 10%concentration is recom-, mended.

, Per cent (2) Sulfonated castor oil, 15% water conten 50 'Oleic a i 50'A 10% solution of the above formula in cleaning naphtha produces acleaning solvent capable of containing 1% moisture. The percentageconcentration of this absorbefacient in the cleaning solvent iscritical.

, Per cent (4) Hydrogenated sulfonated anthracene..- 14.5 Naphtha 40.5Oleic acid 17.5 Water 7 15.0 Sodium oleate- 12.5

- Ah 8% concentration in naphtha is recommend-v ed. After being depletedof moisture. the solution reabsorbs it, but considerable agitation is iI Percent (5) Sulfqpated hydrogenated anthracene- 7.55 Naphtha 21.00Oleicacid 25. -Water 11.75- Potassium oIeate 26.125

Mono-butyl-etherof ethylene glycol- 7. B5

This formul a absorbs moisture very readily and its concentration in thenaphtha solution is not critical. A 10% concentration is recommended.

Per cent (6) Oleic a i 25 Naphtha 25' Pure mahogany sodium sulfonate t50 This material re-absorbs the moisture readily and can be used in anycleaning solvent suitable for dry cleaning in almost any proportions. Arecommended concentration is 6%.

A 6% solution is suitable for absorbing the usually desirable amounts ofmoisture.

These various formulae exhibit to varying degrees the properties of theideal absorbefacient to be used in practicing this invention. Certainones of the absorbefacients tend to cause bleeding of some dyestufls oncertain fabrics but are entirely satisfactory for other classes ofarticles. The use of some of the absorbefacients would requireappreciable expert control of the conditions of the cleaning process toinsure best results or would be usable only where this control wasavailable. v

Of the various formulae provided, No. 6 is the preferred and recommendedone because it possesses all of .the requisite properties previouslydiscussed, can be used with all of the types of cleaning solvents atpresent employed for dry cleaning, can be used safely and successfullyon a commercial scale without supervision of. the cleaning processby'skilled chemists, and can be used successfully on all types offabrics adapted to be cleaned by this general process.

Moreover, Formula No. 6 may be used in most dry cleaning plants as atpresent constituted without any substantial changes of equipment ormaterial changes in handling and routing the fabrics through the plantexcept as herein specified.

Formulae Nos. 7 and 8 .are characterized by very ready absorption ofmoisture .and are suitable for use for fabric cleaning purposes withoutthe exercise of an undue amount of chemical control. These formulae arecharacterized by the use of partially saponifled oleic acid and amaterial or reagent mutually miscible with oil and water. This reagentmay be termed an absorption assistant. Cyclohexanol is the absorptionassistant of Formula No. land ethylene glycol. mono butyl ether. ofFormula No. 8. Other mutualiy miscible materials which may be used asabsorption assistants (though with varying degreesof safety on dyedfabrics), comprise butyl acetate, isopropyl alcohol, ethyl alcohol,diacetone alcohol, ethylene glycol mono ethyl ether acetate,

and diethylene glycol mono butyl ether. Ab-.

sorption assistants which. tend to be taken up by the fabrics must beperiodically replenished.

In regard to these Formulae Nos. 7 and 8, it

must be noted that the presence of free fatty acid is desirable torender a fatty acid soap truly soluble in the cleaning solvent in thepresence of moisture, and that the absorption assistants augment thepower to take up the required quantitles of moisture rapidly and in theproper condition of dispersion.

" Mahogany sulfonates are the salts of mahogany acids which are formedin the oil layer or A layer in the refining of medicinal white oil andthe like by the use of fuming sulfuric acid and/or sulfur trioxide. TheUnited States Patent to Divine, No. 1,493,111, issued May 6. 1924,discloses mahogany sulfonic bodies suitable for the practice of thisprocess.

Great care must be used in employing this invention with chlorinatedcleaning solvents to avoid the formation of harmful quantities ofhydrochloric acid and therefore throughout this description theinvention has been disclosed in relation to the equipment of an open,naphthaprocess plant, though it must be understood that other types ofequipment and plants may be used with appropriate minor modificationswell within the skill of the art.

I have observed that in the actual practice of the process hereindisclosed in commercial dry cleaning plants, silk or rayon fabrics (orin mixture thereof) which have been finished with water sensitive sizessuch as the starch or dextrine sizes are very much improved inappearance. In fact, the fabrics frequently look much better than theydid when they were absolutely new. The moisture which is absorbed by thefabrics in the process seems to revitalize the size, seems to level itto compensate for size which may have been removed by wear, andaltogether restores the uniformity of the finish of the fabric andprovides a lustre which is highly attractive and desirable. By this itis meant that not only is water soluble. soil removed from the fabricsin the cleaning process but that the physical condition of the finish ofthe fabrics is actually changed.

Claims directed to the general dry cleaning process herein disclosed,including claims directed broadly to humidifying the cleaning solvent,or

using an absorbefacient for charging the solvent with moisture inrelation to the batch being cleaned, appear in my original co-pendingapplication Serial No. 590,981, now issued into Patent No. 1,911,289,dated May 30, 1933, whereas the claims of this application are alldirected to a method of affecting the appearance of fabrics finishedwith water sensitive sizes.

Having described the invention, I desire to be limited only by thefollowing claims.

I claim: I 1. The process of leveling the size ofsilk and co rayonfabrics finished with a water sensitive size,

. tion until the fabrics being treated have absorbed said moisture fromthe dry cleaning solvent.

2. The process of leveling and brightening the V appearance of silk andrayon fabrics finished with a water sensitive size, said process,comprising, agitating said fabrics in a dry cleaning solvent of thegroup consisting of volatile and chlorinated hydrocarbons in which isdispersed moisture in amount equal to between five and fifteen percentof the weight of the fabrics.

3. A new art of leveling the size and brightening the appearance of silkand rayon fabrics finished with water sensitive sizes, said artcomprising, treating said fabrics in an optically clear dispersion ofmoisture in a cleaning solvent of the group consisting of volatile andchlorinated hydrocarbons, the weight of the moisture dispersed in saidsolvent plus the weight of the moisture already in the fabrics beingequal to between substantially five and fifteen percent of the weight ofthe fabrics.

4. The process of leveling the size of silk or rayon fabrics finishedwith water sensitive sizes, comprising, removing substantially all ofthe moisture from the fabrics, then agitating said fabrics in adispersion of moisture in a cleaning solvent selected from the groupconsisting of volatile and chlorinated hydrocarbons, said solvent beingsubstantially optically clear, the dispersed moisture being equal tobetween substantially. five and fifteen percent of the weight of thefabrics being treated.

5. The method of leveling water sensitive sizing of silk and rayonfabrics without removing said sizing from said fabrics, comprising,causing said fabrics to absorb evenly and uniformly from substantially 5to 15% of moisture based on the weight of said fabrics by treating saidfabrics with a very fine dispersion of moisture in an organic drycleaning solvent of the group consisting of volatile and chlorinatedhydrocarbons.

6. The method of leveling water sensitive sizing of silk and rayonfabrics without removing said sizing from said fabrics, comprisingcausing said fabrics to absorb evenly and uniformly a quota of moistureappropriate to level said sensitive sizirm, but not exceedingsubstantially 15% of moisture based on the weight of said fabrics, bytreating said fabrics with a very fine dispersion of moisture in anorganic dry-cleaning solvent of thegroup consisting of volatile andchlorinated hydrocarbons.

